CoCoRaHS

CoCoRaHS is a unique, non-profit, community-based network of volunteers of all ages and backgrounds working together to measure and map precipitation.

Wednesday, August 13, 2008

Unusual Storm System

A large area of low pressure has brought some very beneficial rain to states in the southeast, along with some cool air for this time of year.

It is unusual because this type of storm system is more common in the winter months.

Typically in the south cold fronts and areas of low pressure just don't happen in the summer. About the only hope for precipitaton is from a land-falling tropical system or your every day garden variety pop-up showers and thunderstorms that result from daytime heating and all the abundant moisture in the air.

I think just about every CoCoRaHS station in Alabama and Georgia reported rain on Tuesday.

This area really needed that type of widespread rainfall so I am glad that Mother Nature threw them a curve ball.

Speaking of curve balls, we have one coming down the east side of the Rockies this weekend.

Our highs here in Denver will struggle to reach 70 degrees on Friday and Saturday. Lows should be in the upper 40s and lower 50s.

Our mountains will see a rain/snow mix above the treeline -- which is approximately 11,000 feet.

Fall will be here before you know it -- see make the most of these late summer days.

Today's Lesson

If you love weather, then you want to live in the middle latitudes -- between about 30 and 50° N -- which happens to be where the United States is located.

It is in this region where most of the exciting weather is found as cold air moves down from the Arctic and warm air moves up from the Equator.

Big areas of low pressure (also called middle latitude cyclonic storms) sweep across the country along with a front and make for exciting times.

A front is an area where there is a sharp change in temperature, humidity and wind direction.

Every state in the union can boast an example -- but I think one of the better examples is Missouri -- since there is a major city on each side of the state.

If you were to look at a weather report and Kansas City was 75 degrees with a 38 degree dewpoint, and St. Louis was 90 degrees with a 65 degree dewpoint -- you could easily tell there was a cold front sitting somewhere in between.

On one side it is hot and muggy (St. Louis) and on the backside is is cooler and drier (Kansas City).

You can also tell alot about the weather by observing the wind direction.

Wind is the horizontal movement of air. And the wind direction is the direction from which the wind is blowing, not the direction it is blowing toward.

Southerly winds typically transport warm, moist air while northerly winds are often dry and cooler.

Easterly winds usually mean unsettled weather ahead while westerly winds are often associated with tranquil weather.

But this is all relative on where you live and the topography around you.